As electronic devices have become more common, the number of small electronic components that require testing has increased dramatically. In response to this need, automated test equipment capable of testing large quantities of parts at an exceedingly high speed has become commonplace. There is equipment of this type capable of processing components at a rate of 10,000 parts per hour.
In the testing of electronic components, certain problems are commonly experienced and are often exacerbated as the size of the component being tested decreases. For example, many machines produce vibrations during operation (especially by the mechanism that transports the component between different areas of the machine) that adversely affect the component during its transport and testing. This effect is magnified by the extremely low mass of a small electronic component. For example, the prior art patent issued to Herrman (U.S. Pat. No. 4,747,479) teaches a machine that includes a conveyer belt system for transporting parts from a feed station to a test station. It has been found that the slight vibratory movements of the flexible belt cause relatively substantial movements of the parts carried on the belt. This creates a limit in the machine speed since the parts must remain on the belt during transport and also be stable during testing.
Another problem experienced with testing of electronic components using the prior art devices is that random or background electrical or magnetic fields in the area of the testing station will adversely affect the component's test results. This limits the usefulness of the equipment and creates some degree of uncertainty about the acceptability of the tested parts. In an attempt to overcome this problem, various shielding arrangements have been added to some of the prior art equipment. However, the design of the equipment necessitates the use of a significant amount of shielding. This increases the cost of the machine. In addition, the design limits the effectiveness of the shielding whereby accurate testing above a frequency of 30 megahertz is virtually impossible.